Additives of PPO

Additives of PPO:

1. Flame retardants

2. Glass fibers

Grades of PPO

They are available in the following grades. 

-  Glass reinforced 

-  Foam grade

-  Plating grade

-  High modulus grade

-  Blow moulding grade

-  Injection moulding grade

Processing considerations  of PPO

-  Typical cylinder temperatures are about 280-300°C and mold temperatures 100 – 120°C. 

-  If overheated, the material oxidizes resulting in poor finish and streakiness. Because of this it is advisable to  purge machines before they are cooled down after molding. 

-  The melt of PPO are almost Newtonian  viscosity being almost  independent of shear rate. 

-  Due to their extremely low moisture absorption  PPO resin can be molded without the need of drying. 

-  Surface defect in case of due to the trapped moisture, can be avoided by proper drying.

-  Drying temperature vary with the resin grades. Temperature of  110°C for 2 hours are recommended for drying. 

They can be processed by the following processing techniques.

-  Extrusion

-  Foam moulding

-  Thermoforming 

Surface Finishing of PPO

- Screen printing and hot embossing are common. 

- Alkyd, acrylic and epoxide based lacquers are used for coating. Vacuum metallizing is used for metal finishes.

Machineability of PPO

Joining

 Welding 

Surface temperature of 260 to 2900C are selected for heated tool welding. Friction welding takes place at speeds of 1200 rpm and contact pressure of 20 N mm-2. Ultrasonic and resistance wire welding are also used.

 Bonding

 PPO can be bonded using solvents such as dichloroethylene, toluene, chloroform or 950, dichloroethylene with 5% carbontetrachloride .High tensile and shear strength are achieved with rubber, epoxide, resin, silicon, cyanoacrylate and PU adhesives.

Applications of PPO

Automotive: Instrument panels, steering column, cladding, central consoles, loud speaker housings ventilator grills, nozzles, parcel shelves, radiator tanks, cable connectors, bulb sockets, air inlet and outlet grills and outer mirror housings. 

Electricals/Electronics: Television tuner strips, microwave insulation component, transformer housings. Computer terminals, printers, modems, typewriter bases, video games, copier, capacitor   casings, outlet boxes, coil bobbins, smoke detectors, intrusion alarm, motor covers and switches. 

Miscellaneous:

Water pumps, water meters, sprinkler systems, hot water tank, washing machine parts, welder’s protective visors, tennis racquets, textile components and valves for drink vending machines. 

Blends of PPO:

- Polyphenylene oxide is completely miscible with polystyrene in all proportions. The glass transition temperature of these blends change smoothly with composition. 

- These blends with 25-60% (weight) of PPO, designed for injection or blow moulding, extrusion calendering, thermoforming and reinforced with 0-30 weight percentage glass fiber. 

- They have good processability, toughness, flame retardance, dimensional stability, resistance to hot water, economy, HDT (95-150°C), low density and moisture absorption. 

PPO / Nylons 

- These are blends (compatibilized) with 40-60 weight percentage of nylon. 

- PPO provide excellent heat resistance, toughness and nylon (crystalline) resists oils, gasoline and solvent, PPO / Nylons alloys have a lower density, higher toughness and show less tool/machine wearcompared to machine filled Nylon.

- Polyamide grades are used for automotive body panels which require paint oven temperature upto 175°C.

- PPO/Nylon grades are used in fluid handling applications which require chemical resistance, dimensional stability and  heat resistance.